Thermodynamic analysis of an integrated solid oxide fuel cell, Organic Rankine Cycle and absorption chiller trigeneration system with CO2 capture

Abstract

A novel trigeneration system which integrates a SOFC system, an Organic Rankine Cycle (ORC), and an ammonia water absorption chiller with a CO2 capture system is proposed and investigated. The exhaust gas from SOFC anode combusts with pure O2 instead of air and thus the combustion products mainly consist of CO2 and H2O, which the CO2 can be captured easily by the condensation method; in SOFC cathode side, a series-connected ORC and ammonia water absorption chiller heat recovery system which can produce power, heat and cooling is employed to recover the waste heat of SOFC cathode exhaust gas. A mathematical model is developed to study the system performance under steady-state conditions. The calculated results show that the net electrical efficiency and the exergy efficiency of the integrated system can reach 52.83% and 59.96%, respectively. The trigeneration efficiencies of the combined system without and with CO2 capture are 74.28% and 72.23%, respectively. The effects of the SOFC inlet temperature, the current density, the steam-to-carbon ratio, the pinch point temperature difference and the turbine II inlet pressure on the trigeneration system performances are investigated in detail. The research achievement in this paper can provide the useful reference for SOFC based trigeneration system with low energy consumption for CO2 capture.